"Lumen’s technology is based on the very real metabolic measurement called respiratory quotient (RQ). For decades scientists and dieticians have used RQ to determine how a body is metabolizing macronutrients and which energy pathways are being individually favored, from carbohydrates to fat.
The RQ value for a person is calculated by measuring the volume of carbon dioxide produced by the body, compared to the level of oxygen consumed by the body. Traditionally, this is tested using a complex breathing apparatus connected to a computer that tracks your breathing for around 20 minutes. RQ is usually presented as a decimal between 0.6 and 1.0, with 1.0 indicating your body is metabolizing energy mostly from carbohydrates, and around 0.7 signaling your body is mostly burning fat.
RQ is most certainly a real, and valuable, metabolic benchmark that scientists can derive a great deal of information from regarding an individual’s overall health. Lumen’s big claim is that it can generate an accurate RQ measurement from just a single breath.
The company producing the device claims to have developed the technology over the course of several years of research. Multiple studies are said to have been conducted at institutions such as San Francisco State University and Tel Aviv Sourasky Medical Center, and verified it achieves similar RQ measurements when compared to a 60 minute medical-grade analytic device.
Instead of delivering your RQ value as a dry decimal, Lumen translates that data into a spectrum that spans fat to carbs and then suggests meal plans that can optimize your day according to your specific metabolic profile. Via a paired app, the system can subsequently track your sleep and activity to constantly modulate its recommendations."
What you mean is its not beneficial toward nutrition/ health. I agree, but a waste of money is up to the individual. It could be a fun toy for some. Not that its worth doing, but it might be fun to see how your number changes over holidays vs training season, if some one wants to try a fad diet (dumb, but hey they’re gonna do it), want to compare your "number’’ with a training partner, etc. This just reminds me of all the useless metrics from garmin stuff, but for some it can still be an entertaining toy
Broadly I respect your opinion on here, and I know you dislike ‘fad’ ideas for good reason.
However individuals definitely burn different % of carbs vs fats at different output levels (to use a non specific generic term) and it has to be an advantage for long events if this can be trained to increase the fat%.
Sami Inkinen did a good blog about how he changed his ‘fat burning threshold’ on the bike and the implications for racing ironman. He’s certainly not stupid and has an obsession with measuring things (as well as the resources to do as much as he wants.) so I am fairly confident it is accurate.
Broadly I respect your opinion on here, and I know you dislike ‘fad’ ideas for good reason.
However individuals definitely burn different % of carbs vs fats at different output levels (to use a non specific generic term) and it has to be an advantage for long events if this can be trained to increase the fat%.
Sami Inkinen did a good blog about how he changed his ‘fat burning threshold’ on the bike and the implications for racing ironman. He’s certainly not stupid and has an obsession with measuring things (as well as the resources to do as much as he wants.) so I am fairly confident it is accurate.
I assumed he meant that the device wouldn’t give accurate/actionable data, rather than that it wouldn’t be useful to know what % of carbs vs fat you’re burning. Certainly if it was possible to get accurate data from a single breath then I’d have thought that would be extremely useful. No idea on the science behind this though!
Spoke with my nutricionist about it. Science wise it does make sense if they are really able to deliver a fully functional device. Is it absolutely necessary?! No ! But as most gadgets today, its at least interesting to get those insights in my opinion.
There is no good evidence, nor any sound logic, to support the claim that knowing the substrate mix that an individual oxidizes is helpful to either improving performance or losing weight. Minaturized consumer devices such as this one, even if they live up to their accuracy claims, are therefore a waste of money.
Wouldn’t the logic be that if you have a reasonable estimate for total calorie burn (derived from power meter and/or HRM), and you know what % of fat vs carbs you’re burning, then you can more accurately gauge how many carbs you need to be taking on? Given that taking on insufficient carbs leads to bonking, and that taking on too many increases the chances of GI issues, I’d have thought that anything which helps you get a bit closer to the optimal carb intake would be useful.
When races go wrong, nutrition seems to be one of the top culprits (alongside overbiking), so it’s certainly an area plenty of people could use some help with.
If that’s the case then agree it wouldn’t be much use, but I couldn’t see that in the original link. Did I miss it or do you have other knowledge about how this would (or wouldn’t…) work?
During exercise, you can’t absorb and utilize ingested carbohydrates nearly as rapidly as you oxidize carbohydrate. There is therefore no relationship between the optimal rate of supplementation and the rate of oxidation. Moreover, this device only measures the relative contribution of carbohydrate, not the absolute rate. Thus, even if you could spare a breath here or there to breathe into it, the data would not be useful.
Thanks, that helps. I still don’t quite get it - I’m aware you can’t absorb carbs as quickly as you burn them, but the relative burn rate is still useful info surely?
E.g. If I know from my power meter/HRM that I’m burning 1000 cals/hour, then if this device could tell me that relatively speaking I’m getting 50% of those calories from carbs, then I know I’m using 500 carb cals per hour. I can’t absorb 500 cals/hour, but let’s say I’m taking on 300, for a deficit of 200 cals/hour. Let’s assume I’ve got 1500 cals of carb in my body when I start, that means 300 cals/hour is enough to get me through 7-8 hours of racing which is more than enough to get through a70.3. Change that carb burning percentage to 60%, and suddenly my deficit is 300/hour and I’m running low on carbs after 5 hours, which is touch and go for a 70.3 for many AGers. So I either need to take on more carbs, slow down, or train my ability to burn fat better.
Does that make any sense? Or are calorie estimations from power/HR so inaccurate that it all becomes meaningless?
Could this devise be used to assertain the wattage at which one reaches say 50% burning carbs and 50% fat, or the wattage at which one is burning close to 100% fat?
Might this data be of some interest to view alongside wattage at MLSS?
What might the carb / fat burning percentages / ratio be at MLSS?
Thanks, that helps. I still don’t quite get it - I’m aware you can’t absorb carbs as quickly as you burn them, but the relative burn rate is still useful info surely?
E.g. If I know from my power meter/HRM that I’m burning 1000 cals/hour, then if this device could tell me that relatively speaking I’m getting 50% of those calories from carbs, then I know I’m using 500 carb cals per hour. I can’t absorb 500 cals/hour, but let’s say I’m taking on 300, for a deficit of 200 cals/hour. Let’s assume I’ve got 1500 cals of carb in my body when I start, that means 300 cals/hour is enough to get me through 7-8 hours of racing which is more than enough to get through a70.3. Change that carb burning percentage to 60%, and suddenly my deficit is 300/hour and I’m running low on carbs after 5 hours, which is touch and go for a 70.3 for many AGers. So I either need to take on more carbs, slow down, or train my ability to burn fat better.
Does that make any sense? Or are calorie estimations from power/HR so inaccurate that it all becomes meaningless?
Calorie estimates from HR are inaccurate, from power they at least have a margin of error based on an individuals efficiency (which is not static). Add that to the margin of error of this device, plus the discrete points in time that you’re able to take a sample…
… At that point, if you’re going to need to supplement carbohydrates you might as well do it at the maximal rate that your body can manage effectively. IMO anyway.
Could this devise be used to assertain the wattage at which one reaches say 50% burning carbs and 50% fat, or the wattage at which one is burning close to 100% fat?
Might this data be of some interest to view alongside wattage at MLSS?
What might the carb / fat burning percentages be at MLSS?
In a non-glycogen depleted state, you can assume it’s basically 100% Carbohydrate.
Thanks, all makes sense. Basically by the time you aggregate 3 numbers which are all estimates (calorie burn rate, fat vs carb rate, and glycogen stored in the body before you start) the output becomes meaningless.
I guess most of us have enough training and racing in the bank to have a pretty good idea of how long we can go without carbs before hitting problems, and how many carbs we can absorb per hour. Haven’t bonked too many times, but enough to know the warning signs and how to avoid it.
If you want to win races, you need to burn carbohydrates (and fats) and also absorb them as quickly as possible. That means training as much/hard/long as possible, while practicing carbohydrate supplementation during exercise. How does a device such as this one change things?
